You need to know the least common denominator (LCD) of 9 and 15 if you want to add or subtract two
fractions with 9 and 15 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 9 and 15 is 45.
Here is a math problem example where you need to know the LCD of 9 and 15 to solve:
3/9 + 2/15 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
45/9 = 5
45/15 = 3
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 5 = 15
2 x 3 = 6
Step 3) Put it all together to solve the problem:
15/45 + 6/45 = 21/45
= 3/9 + 2/15 = 21/45
It's that easy! Once again, the lowest common denominator (LCD) of 9 and 15 is as follows:
45
What is the Least Common Denominator of 9 and 16?
Go here for the next Least Common Denominator on our list that we calculated.

